South Yorkshire Police want to hear from anyone who witnessed a single vehicle collision.
At around 10.50pm on Saturday it is reported a silver Vauxhall Zafira was travelling along Mexborough Greens Way fly-over in the direction of Bank Street when it was in collision with fly-over railings.
The 43-year-old driver suffered life-threatening injuries and remains in hospital. A 46-year-old woman passenger suffered minor injuries.
Witnesses are invited to call 101 or email firstname.lastname@example.org quoting incident number 1289 of 26 November 2016.